Process for coating a support with a polyamide plastic material

ABSTRACT

1. A PROCESS FOR COATING A SUPPORT WITH A POLYAMIDE PLASTIC MATERIAL, COMPRISING COATING THE SUPPORT WITH AN IONIC ACID POLYAMIDE SOLUTION IN THE FORM OF A PASTE AND THE COAGULATING THE COATING BY SPREADING ON THE COATED SUPPORT A PULVERIZED SALT CHOSEN FROM THE GROUP CONSISTING OF MONO-AMMONIUM PHOSPHATE, DI-AMMONIUM PHOSPHATE, MONO-SODIUM PHOSPHATE, DI-SODIUM PHOSPHATE AND TRI-SODIUM PHOSPHATE.

United States Patent O 907008 Int. Cl. B44d 1/44; B44c N04 US. Cl.117-622 3 Claims ABSTRACT OF THE DISCLOSURE A process for coating asupport with a polyamide plastic material, wherein the support is coatedwith an ionic acid solution of a polyamide paste, and then the solutionis made to coagulate by pulverizing on the coated support a salt such asa sodium phosphate of an acid weaker than the acid of the solution. Theprocess may be used, for example, in the coating of panels made of woodor agglomerated fibers, thereby producing decorative surfaces which donot require painting or additional coating.

This application is a continuation-in-part of application Ser. No.15,946, filed Mar. 2, 1970, now abandoned.

This invention relates to a process for depositing plastic material on asupport; such process is employed in particular in the manufacture ofdecorative panels.

In their Patent Application filed in France on Dec. 6, 1968 for aProcess of Obtaining New Materials and Products Obtained Therefrom, nowFrench Pat. No. 1,602,721, published I an. 18, 1971, the Applicantproposed a new process having multiple applications. The presentinvention constitutes at least one of these applications in that itdiscloses a new process for coating surfaces of all natures, by means ofplastic material.

There are already various processes in existence which are usedparticularly for decorative purposes, such processes enabling a supportto be coated with a plastic material. A certain number of theseprocesses use pro-fabricated sheets of plastic material which are thenmade to adhere to a support. On the contrary, others directly cover thesupport with a plastic material, this operation generally being effectedunder temperature and pressure conditions which are ditferent from theambient conditions leading to finished products that may be used forproducing furniture, partitions, etc., without its being necessary todecorate them later.

The present invention belongs to this second category of coatingprocedures, but proposes a new process which is carried out withoutspecial equipment, under the ambient conditions of temperature andpressure. In addition, due to its high speed of execution, the newprocess enables products to be obtained which are of a lower cost price.

The invention therefore has among its objects the provision of a processfor coating a support by a polyamide plastic material, according towhich the support is coated with an ionic acid solution preferably inthe form of a polyamide paste, then the solution is caused to coagulateby pulverizing on the coated deposit a salt of an acid which is weakerthan that of the ionic solution.

The ionic acid solution of a polymer will be of the type such as thatdescribed in the above-mentioned French Patent, that is to say, it willcontain monomeric units having both at least one hydrogen of acidcharacter and at least one acid radical bonded with a carbon by a bondof electrovalent type. As was explained in said French Patent, such asolution contains monomeric units which later may be polymerized orcoagulated.

Patented Oct. 22, 1974 In the particular case of the present invention,the monomeric units are amides and the coagulation is obtained by meansof a salt, for example a monoor diammonium or a sodium mono-, diortri-phosphate, whose granulometry will be responsible for the finenessor roughness of the final coating.

On the other hand, dyes, in particular pigments or acid dyes such asthose known commercially as Kiton, may be added to the solution beforethe support is coated.

EXAMPLE I A coating was produced on a large number of wood supports froma solution comprising 300 cc. hydrochloric acid at 22 'Baum, 200 cc.water, and 200 g. of 6 Lilion polyamide. Lilion is the well-knowncommercial name for polycaprolactam. According to the conditions ofambient temperature, this solution becomes homogeneous and pasty; it maybe used within a period of time between 5 minutes and 2 hours. After thesupport has been coated with agglomerate particles or the like, a monoordi-ammonium phosphate is pulverized and is spread upon the coating.Coagulation is almost instantaneous, and the coating hardens withoutdelay.

The resulting product is a support coated with a film of plasticmaterial with a granite-like appearance, the fineness of which dependsupon the granulometary of the phosphate. If desired, washing may then becarried out with a basic solution, so as to eliminate any trace of acidfrom the coating and to increase its hardness. Too great a shrinkage ofthe plastic film upon drying is also thereby avoided.

EXAMPLE II 45 kg. of polyamide 6 polycaprolactam was dissolved in kg.hydrochloric acid 11 N. At the end of dissolution (2 hours at ambienttemperature), the solution was filtered and the viscosity was adjustedto the desired value with the aid of hydrochloric acid 11 N. Thesolution was injected into the circuit of a curtain coating apparatus.The supports to be covered, for example, sheets of lignocellulosicmaterials, were then coated with the solution; in general, in order toobtain a correct covering 1 kg. of solution was deposited per squaremeter. Pulverizled trisodium phosphate was deposited on the layer ofsolution, at a rate of 1 to 2 kg. per square meter. The coating was thenallowed to coagulate for 1 hour at ambient temperature, and then theexcess salt was brushed off.

EXAMPLE III Under the same conditions as in Example II, 45 kg. of nylon66 (polycondensate of hexarnethylene diamine and adipic acid) wasdissolved in 95 kg. of hydrochloric acid 11 N, the solution being coatedupon a panel. Coagulation of such coating was obtained by means ofpulverized trisodium phosphate. The result was the same as in ExampleII.

EXAMPLE IV A similar result obtained by dissolving 5 0 kg. of nylon 2(polyglycine) in kg. of hydrochloric acid 5 N, the solution being coatedupon a panel. Coagulation of the coating was obtained by means ofpulverized trisodium phosphate.

EXAMPLE V 20 kg. of polyamide 11 was dissolved in 70 kg., of nitric acidat 36 Baum The solution thus obtained was used under the conditionsindicated in Example II; the coagulation was provoked by pulverizedtrisodium phosphate.

The coatings obtained in the various Examples I-V above have propertieswhich have already been mentioned in the French Application mentionedhereinabove, in particular a semi-permeability, and a considerableresistance to various chemical agents.

In this respect, it should be noted that the chemical resistance of thecoating is higher than of the polymers introduced into the startingsolution. The advantage of the process according to the invention oversimilar processes such as those calling upon the transfer of thepolyamide may thus be readily appreciated.

In addition, the specific properties of salt, for example, theresistance to flame in the case of ammonium phosphates, are transferredto the whole of the coating and may consequently contribute to theefficient protection of the support. It is to be noted that ammoniumphosphate may be substituted for the various sodium phosphates employedin the above examples.

On the other hand, it should be emphasized that the coagulation of thesolution reduce the crosslinking of the polymers reconstituted from themonomeric units contained in the solution. Therefore, if this solutioncomprises dyes, the coating is colored in its mass, thus preventing anyaging or degradation of its appearance. Of course, for certain artisticor decorative applications, it is possible to coat the support with aplurality of layers of colored solutions in different ways, before orafter coagulation by pulverizing a salt.

Finally, as the hardness of the coating is adjustable by the compositionof the solution, the nature of the salt and the possible washingtreatment, it is possible to provide a pumicing of the coating after itsmanufacture.

Although the invention is illustrated and described with reference to aplurality of preferred embodiments thereof, it is to be expresslyunderstood that it is in no way limited to the disclosure of such aplurality of embodiments, but is capable of numerous modificationswithin the scope of the appended claims.

What is claimed is:

1. A process for coating a support with a polyamide plastic material,comprising coating the support with an ionic acid polyamide solution inthe form of a paste and then coagulating the coating by spreading on thecoated support a pulverized salt chosen from the group consisting ofmono-ammonium phosphate, di-ammonium phosphate, mono-sodium phosphate,di-sodium phosphate and tri-so dium phosphate.

2. A process for coating a support with a polyamide plastic material,comprising coating the support with an ionic acid polycaprolactamsolution in the form of a paste and then coagulating the coating byspreading on the coated support a salt of an acid weaker than that ofthe polycaprolactam solution.

3. A process as claimed in claim 2, wherein the salt is chosen from thegroup consisting of mono-ammonium phosphate, di-ammonium phosphate,mono-sodium phosphate, di-sodium phosphate and tri-sodium phosphate.

References Cited UNITED STATES PATENTS 1,875,054 8/1932 Loetscher 117-332,056,406 10/1936 Mayne 117-42 2,185,217 1/1940 Moore 11733 2,684,3057/1954 Quinlivan 11733 2,952,562 9/1960 Morris et al. 11762 3,202,5318/1965 Dowd et al 117-62 3,248,254 4/1966 Zenit et a1 117-33 3,272,6459/1966 Duhoo 11733 3,368,912 2/1968 Adamis 11742 3,402,093 9/1968 Riva11733 3,526,531 9/1970 Asano et al. 11762.2 3,577,257 5/1971 Hutzler etal. 117-33 3,697,437 10/1972 Fogle et al 11762.2

3 MICHAEL SOFOCLEOUS, Primary Examiner US. Cl. X.R.

1. A PROCESS FOR COATING A SUPPORT WITH A POLYAMIDE PLASTIC MATERIAL,COMPRISING COATING THE SUPPORT WITH AN IONIC ACID POLYAMIDE SOLUTION INTHE FORM OF A PASTE AND THE COAGULATING THE COATING BY SPREADING ON THECOATED SUPPORT A PULVERIZED SALT CHOSEN FROM THE GROUP CONSISTING OFMONO-AMMONIUM PHOSPHATE, DI-AMMONIUM PHOSPHATE, MONO-SODIUM PHOSPHATE,DI-SODIUM PHOSPHATE AND TRI-SODIUM PHOSPHATE.